Dispersion Blade and Propeller Together?

INDCO

At INDCO we talk daily with customers who use our equipment to achieve their mixing process needs. While most are using what we would describe as conventional equipment setups and procedures we do encounter those that are less so. One example that we are sometimes asked about is the use of a dispersion blade and a marine style or other axial flow impeller in combination on the same shaft. Our response is that we generally do not recommend it for the following reasons:

The dispersion blade and the marine style propeller require distinctly different torque and speed requirements to complete their respective functions. Therefore, either the blade or the propeller is unable to properly perform. The RPM required for the dispersion blade to truly provide dispersion is very high and would likely result in the propeller pumping at too high a rate. Reducing shaft speed may put the propeller in the desired product flow range but the blade is no longer providing enough shear for dispersion. A common method of obtaining product flow and high shear, especially with higher viscosities, is to use multiple mixers turning at different speeds in the same batch. A large impeller driven at low RPM and high torque is often positioned in combination with a separate dispersion blade running at much higher rpm. For particularly viscous materials, a third anchor-type mixer is used with the other two to move product away from the tank wall.

For help with this or any other unique mixing application call INDCO. We are here to assist you.